For decades, the moon had been considered a dead and uninterestingworld by scientists. — Ricardo DeAratanha/Los Angeles Times.

Space scientists have found the strongest evidence yet that water exists on the moon, a discovery that helps complete a picture of a water-rich solar system and that could make colonizing our nearest neighbor in space much easier than previously thought.

Using data from three spacecraft that have made close flybys of the moon in recent years, research teams in the United States say they have found proof that a thin film of water coats the surface of the soil in at least some places on the moon.

"Within the context of lunar science, this is a major discovery," said Paul G. Lucey, a planetary scientist with the University of Hawaii, who was not involved in the current research. "There was zero accepted evidence that there was any water at the lunar surface, [but] now it is shown to be easily detectable, though by extremely sensitive methods. As a lunar scientist, when I read about this I was completely blown away."

The discovery "will forever change how we look at the moon," added Roger Clark, a scientist with the U.S. Geological Survey in Denver and the author of one of three papers — each dealing with data from a different spacecraft — appearing in this week's edition of Science magazine.

For decades, the moon had been considered a dead and uninteresting world by scientists. The Apollo missions of the 1960s and '70s brought back some rocks that contained tiny amounts of trapped water, but scientists at the time decided they had been contaminated by water from Earth.

Proponents of human space travel hope this discovery could put pressure on the White House to follow through with the George W. Bush administration's plans to return to the moon by 2020 and to construct Earth's first off-world colony there.

At the very least, the discovery lends weight to a new view of a friendlier solar system, where water, the lifeblood of biology on Earth, suddenly seems to be everywhere. Last year's Phoenix mission to Mars' polar region found ice just beneath the lander's struts. Ice has been found on Saturn's moon Titan and it covers Jupiter's moon Europa.

Research teams from Brown University, the University of Maryland and the U.S. Geological Survey used spectroscopic measurements taken of the lunar surface by NASA's Cassini and Deep Impact spacecraft, as well as India's Chandrayaan 1 satellite. The instruments on all three spacecraft detected the signature of the OH chemical bond (oxygen and hydrogen) at many places on the lunar surface, including areas subject to daytime temperatures that reach the boiling point of water. The greatest concentrations, however, were found in the coldest regions near the two poles.

Detecting the OH bond is not a sure indicator of water. The instruments could be picking up hydroxyl, which is composed of one oxygen and one hydrogen atom. Water has two hydrogen atoms and one oxygen.

But one of the papers, by research scientists Lori Feaga and Jessica Sunshine of the University of Maryland, found clear evidence for both hydroxyl and water in measurements taken by the Deep Impact spectrometer on June 02 and June 09. "We saw both species," Feaga said.

The amount of water in any one place is tiny. Clark estimated it at about a quart per ton of soil.

The moon "is almost as wet as a bone," Lucey said in an e-mail interview with The Times. "It is in the form of an imperceptible film on soil grains, perhaps several molecules thick."

Unless science makes some technological breakthrough, it would be extremely difficult for future moon colonists to harvest such tiny amounts of water. The research indicates, however, that the water migrates toward the poles — by literally lifting off the soil particles and drifting north and south — when the temperature rises during the lunar day.

When the water molecules land in a colder area near the poles, they are trapped there in higher concentrations, "perhaps high enough to use," Lucey said.

The question of how much water might have accumulated at the poles could be answered on October 09, when NASA's Lunar Crater Observation and Sensing Satellite, known as LCROSS, is set to steer a rocket into a south pole crater called Cabeus A.

The resulting collision, which will send up a dust cloud two miles above the surface of the moon, will be observed and sampled by satellites and observatories on Earth for evidence of water. Cabeus A was chosen because it is in a perpetual shadow, so any water stored there in the form of ice would not melt.

"The results of the present studies lend credence to the lunar polar water hypothesis by providing a proven source of water on the surface of the moon," Lucey said.

If there is water on the moon, where did it come from? One possibility, according to the research teams, is that the water was deposited by one or more comets colliding with the moon. Another is that meteorites colliding with the moon might have unearthed underground sources of water.

Finally, the solar wind, a stream of charged particles flowing outward from the sun, which is mostly made up of hydrogen and helium, could play a role. The solar wind could supply hydrogen to bind with oxygen in lunar soils.

Perhaps ironically, given how many spacecraft have orbited and landed on the moon in the last five decades, two of the spacecraft that made the discovery had other missions besides observing the moon. Cassini's primary mission was to observe Saturn and its major moons, including the bizarre, smog-choked Titan. The measurements of the Earth's moon were taken in 1999 as Cassini was on its way to Saturn.

Deep Impact shot a rocket into the comet Tempel 1 in 2005 to find out what a comet is made of, but has since been given other jobs, including rendezvousing with another comet. Chandrayaan 1, India's first moon-orbiting satellite, was launched in October 2008.

All three spacecraft carried spectrometers, which operate by breaking down the light reflected off the surface of the moon. Because every chemical molecule has a different light wavelength signature, scientists analyzing the spectrograph can tell what the surface is made of. The reason the Deep Impact instrument was able to see both water and hydroxyl, Feaga said, was because it has a larger bandwidth than the instruments carried by Cassini and Chandrayaan.

"It is astounding to find water at all latitudes on the moon and in places where the temperature is hotter than boiling water on Earth," Clark said.

The discovery comes at a pivotal time for America's space program. Former President Bush set NASA on an ambitious course to return to the moon by 2020, and then travel on to Mars. But a presidential commission recently found that without a significant increase in its budget, NASA won't be able to reach either goal.

It's unclear how this discovery will affect the debate in Washington over NASA's future, but the presence of water on the moon would presumably make colonization much easier. Water would not only be valuable for drinking, but it could also be used to make oxygen for breathing and to make rocket fuel for trips to and from Earth.

"Perhaps the most valuable result of these new observations is that they prompt a critical reexamination of the notion that the moon is dry," Lucey said. "It is not."

A NASA spacecraft and its trusty rocket stage are drawing ever closer to the moon to intentionally crash to their doom Friday, all in the name of science.

The cosmic collisions are expected to kick up tons of moon dirt in giant debris plumes that will then be scanned for signs of water ice suspected to be buried beneath the floor of a permanently shadowed crater at the lunar south pole.

"Everybody is feeling very excited," said Victoria Friedensen, NASA's program executive for the LCROSS mission at the heart of the moon crash. "There is a great sense of anticipation."

Moon crashNASA launched the LCROSS probe in June along with a powerful lunar orbiter that is currently circling the moon to determine whether water ice, which could be a vital resource for astronauts in the future, actually exists in the perpetual darkness of craters at the moon's south pole.

Since then, the $79 million LCROSS — short for Lunar Crater Observation Sensing Satellite — has made three long loops around the Earth while attached to an empty Centaur rocket stage, its first weapon in the upcoming lunar double whammy.

The two vehicles are due to separate late tonight and the first impact is set for 7:31 a.m. EDT (1131 GMT). That's when the 42-foot (13-meter) long Centaur rocket stage will plow into the crater Cabeus at the moon's south pole. NASA will start broadcasting the event live on NASA TV at 6:30 a.m. EDT (1030 GMT).

Seasoned amateur astronomers may be able to see the crash using 10 or 12-inch telescopes depending on their location, local weather and lighting conditions. [Click here to see how to watch the LCROSS moon crashes.]

The Centaur rocket stage weighs 5,216 pounds (2,366 kg), about as much as a sport utility vehicle, and will slam into the moon at about 5,600 mph (9,010 kph). Researchers believe the blast will create a debris plume about 12 miles (20 km) wide and send moon dirt soaring to heights of 6.2 miles (10 km), where it would be illuminated by the sun.

"It will kick up whatever is on the floor of the crater," LCROSS project manager Daniel Andrews has said. "That may very well include water ice."

But the first crash is only the prelude. Riding aboard the LCROSS spacecraft are nine different science instruments, including cameras that will beam live views of the impact back to NASA's mission operations center at the Ames Research Center in Moffett Field, Calif. Those tools will be used to scan the debris plume for evidence of water ice.

"We expect to see the crater getting closer and closer," Friedensen told SPACE.com.

The 1,664-pound (891-kg) LCROSS shepherding craft will follow its Centaur rocket stage down to make its own crash about four minutes after the initial lunar hit.

More than 20 observatories on Earth, as well as a host of amateur astronomers, museums and volunteers will be watching the two crashes to search for signs of any water ice in the debris clouds. The Hubble Space Telescope and other space-based observatories will also turn their camera eyes on the moon for the event.

"Our last day in flight promises to be the most challenging and the most rewarding for the project," LCROSS flight director Paul Tomkins wrote in his NASA blog today. "Our 112 days in orbit are focused entirely on the last four minutes, after the Centaur impacts our target crater and raises a plume of lunar material for the LCROSS Shepherding Spacecraft to observe for signs of water, but before the Shepherd also impacts the moon."

Unlike other spacecraft that have smacked the moon, like Japan's recent Kaguya probe, Europe's Smart-1 and NASA's Lunar Prospector, the LCROSS impactors will hit at a steep angle in order to get the biggest boom for their buck, mission managers said.

LCROSS has not had a completely smooth ride to the moon. An August glitch forced the spacecraft to use much of its propellant supply, but not enough to prevent its ultimate mission.

NASA also unexpectedly switched target craters last week, choosing the 60-mile (98-km) wide Cabeus over its nearby neighbor Cabeus A because data suggested the new target had a higher concentration of hydrogen — a signal for potential water ice.

Hunting moon water

Scientists already know that some small amount of water exists on the moon, but LCROSS is designed to seek out buried water ice at the lunar south pole — a region where the sun has never shined on some craters with permanent shadows.

NASA scientists say the areas may be the coldest places in the solar system, with temperatures reaching minus 400 degrees Fahrenheit (minus 240 Celsius) in the crater shadows. Finding usable amounts of water ice would be a boon for NASA's vision to send astronauts back to the moon by the mid-2020s.

But Friedensen said that it will take time before scientists know if any water is present in the debris plumes. A few hours after the two impacts, LCROSS scientists will hold a press conference, but will likely only be able to discuss how accurate the hits were, she added.

"We will not be able to talk about how much water is there, if it's water we find," she said. "The science team will need a couple of days, maybe even a couple of weeks to make sure."

The live stream of data from LCROSS will be recorded in triplicate — at the mission control center at Ames and two other sites — to make sure it is saved for posterity, Friedensen added.

Tompkins said that knowing LCROSS will soon meet its fate is a bit sad, even if it was already preordained for the cause of science.

"Well, we all knew it was going to happen. It was inevitable. It was the whole design of the mission," he wrote. "LCROSS was destined to end its wonderfully fantastic journey by intentionally crashing into a permanently shadowed crater at the south pole of the moon."

Get ready for a unique cosmic collision! Early this coming Friday morning (Oct. 9), NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) will end its mission with a bang — literally.

Currently carrying with it the upper stage of the rocket that launched it on its way to the moon on June 18, the game plan is to send that spent rocket motor on a course to smash into the lunar surface.

But just not anywhere on the lunar surface, but to a thoroughly scrutinized crater called Cabeus that lies near the moon's south pole and is enveloped in perpetual darkness. The hoped-for resultant effects will be to find hidden water ice frozen inside the crater.

And for seasoned skywatchers here on Earth, it should also produce a visible cloud of ejected material. However, only knowledgeable amateur astronomers with the right equipment will be a able to detect the event. Others can watch the event live on NASA TV.

Smackdown!

The general belief among astronomers is that over the last few billion years, the moon has been bombarded by countless numbers of comets. The water from most of these comets completely sublimated away but if any settled at the bottom of a crater near the moon's poles, these permanently shadowed regions can keep the water from disappearing, remaining as ice for a very long time.

Cabeus is a relatively flat crater about 60 miles in diameter on the moon's south pole that scientists believe may be one of those special cases that might hold water ice in its perpetually shadowed top soil. NASA initially selected a different target for LCROSS, the nearby crater of Cabeus A, but switched to the larger Cabeus because data suggested it had a higher likelihood of containing hidden water ice.

The impact is scheduled to occur this Friday, Oct. 9 at 11:30 UT. That's 7:30 a.m. EDT; 4:30 a.m. PDT. To convert Universal Time to your local time, go here.

Impact will happen less than 10 hours after the spent LCROSS Centaur rocket motor is released and its Shepherding Spacecraft maneuvers into position to trail the Centaur en route to the lunar surface. The 5,000-pound Centaur, is expected to slam into Cabeus at a sharp angle at a speed of 5,600 mph (9,010 kph).

If all goes according to schedule, the Shepherding vehicle, carrying nine science payloads, will follow the Centaur's plunge into the moon, beaming back data live to the Earth. Like a bullet hitting sand, the Centaur's explosive collision is expected to create a crater roughly 60 or 70 feet wide and perhaps as much as 16 feet deep, in the process dredging up approximately 385 tons of lunar dust and soil — enough to fill nearly 18 school buses. In addition to recording the collision, the Shepherding Satellite will fly through the regolith plume thrown up by the collision, just before it too slams into the lunar surface some four minutes later, kicking up its own smaller plume of debris.

But before it's sacrificed in the cause of science, the 1,500-pound Shepherding Spacecraft will utilize its specialized sensors and will look for water's telltale chemical signature within the larger debris plume created by the Centaur, possibly in the form of ice, hydrocarbons or hydrated materials.

How to watch

NASA wants the amateur astronomer community to join in a "citizen scientist" program. Jennifer Heldmann heads the LCROSS observing campaign. "We would like to have as many eyes and instruments watching the impact as possible because this is the way we'll get the most data and the most information as possible."

Those who live to the west of Mississippi River will have the best opportunity because the sky will still be dark. Those living east of the Mississippi will still have the moon in the sky, but either dawn twilight or — in the case of those living along the Atlantic Seaboard — sunrise will have occurred, making for a much brighter sky background. A dark backdrop will be an important prerequisite, since it's estimated that when the debris plume forms on it will be no brighter than a sixth-magnitude star (the threshold of naked-eye visibility), and quite likely even fainter.

If you want to attempt to see the impact yourself, here are some important points to be aware of:

First, you're going to need a moderately large telescope, somewhere on the order of at least 10 to 12 inches of aperture. Smaller telescopes will probably not be able to do the job and you will definitely not see anything using binoculars. You'll likely need to use magnifications in the 250 to 500-power range to have a legitimate chance of getting a glimpse of the dim impact plume.

Keep in mind that high power dilutes the brightness of an image, as well as aggravates any unsteadiness of detail. As a general rule of thumb that the maximum amount of magnification for any telescope is 50-power per inch of aperture.

"But wait a minute," you may protest, "my telescope comes with a special Barlow lens, that the manufacturer promises will double or even triple the magnification of my eyepiece."

True enough. In fact, that aforementioned 500-power is likely achieved by pushing the scope's highest power eyepiece with that very same Barlow lens, which ultimately will result in a dim, impossibly fuzzy image. If you're a beginner, you need to understand that that using a Barlow lens is similar to enlarging a photograph. The negative — like a telescope's image — contains only so much detail, which can be blown up only so far before all you can see is fuzz! So, if you have a 3-inch department store telescope — even if it is blessed with perfect optics — the claim of 500-power is more than three times the limit of the most practical magnification that it can provide.

The impact will take place at the lunar south pole, or on the lower limb of the moon along the dark portion immediately adjacent to the terminator (the line that separates the illuminated day side and the dark night side of the Moon). Try to keep the very bright sunlit portion of the moon out of the field of view as much as possible.

The plume is expected to be in the shape of a "V" but it will be exceedingly small in size relative to the moon itself. According to NASA's Brian H. Day, the dusty material is only expected to rise about 6 miles (10 km) above the lunar surface. From Earth, that would be equal to about one-quarter of 1 percent of the moon's apparent size or about 5.2 arc seconds.

To try and get an idea of just how large this is, point your telescope toward Jupiter which conveniently shines in the southern part of our current evening sky. Jupiter's disk currently measures 45-arc seconds in diameter; so the dust plume from LCROSS would appear only about 1/9 as large as that!

And the plume — if and when it's visible — will not last very long. The best guesstimates are that it will last no more than 2 minutes.

Observatories expected to participate in the study include the newly refurbished Hubble Space Telescope, Hawaii's Keck and Gemini telescopes, the Magdelena Ridge and Apache Ridge observatories in New Mexico, the MMT Observatory in Arizona and the Lunar Reconnaissance Orbiter (LRO) now circling the moon.

Lastly, you can watch the event live here on NASA TV, beginning at 6:30 a.m. EDT/3:30 a.m. PDT.

At 7:30 a.m. EDT on October 9, a two-ton rocket body will slam into a crater near the moon's south pole. By studying the resulting plume of gas and dust, scientists hope this grand experiment will confirm the presence of ice in permanently shadowed craters at the lunar poles.

The event is the highlight of NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) mission. The LCROSS spacecraft flies behind its empty upper stage, which is targeted to strike the floor of Cabeus crater.

LCROSS will image the impact and provide direct measurements of the plume before it also plunges into the lunar surface. With LCROSS gone, further measurements of the cloud depend on ground-based observatories around the world.

"This is a completely unique mission that will excavate two large holes dozens of meters across on the lunar surface. It will give us composition measurements we wouldn't otherwise be able to get," said Tim McClanahan, a scientist at Goddard Space Flight Center in Greenbelt, Md.

"We realized that ground observers would have difficulty identifying the location," he said. "It's near the lunar south pole, where illumination is poor and the ability to distinguish nearly edge-on craters is problematic. On top of that, LCROSS will hit the crater floor, but we can only see its rim from Earth."

To provide the detailed information ground-based telescopes needed, McClanahan approached Goddard's Scientific Visualization Studio (SVS). The goal was to find a "sweet spot" where factors such as lunar topography, lighting from the sun, and the view from Earth provided the earliest, highest-contrast view of the rapidly changing plume.

"Visualization aided two aspects of the LCROSS mission," said Ernie Wright at the SVS. "It helped us understand how visible the plume will be from Earth and whether the targeted terrain was flat and in shadow."

The project prefers a crater floor because slopes tend to be rocky, whereas lighter, fluffier materials fall to the lowest elevations. "LCROSS scientists want to send up a debris cloud as high as they can," Wright explained, "so they want to hit these light materials."

Scientists think that hydrogen detected in lunar soil by several instruments, including LEND, may be either icy leftovers from ancient comet impacts or accumulated from the solar wind, a stream of particles flowing from the sun. Whatever its source, scientists assume hydrogen collects in low polar elevations where the sun never shines. This dictates an impact in the shadowed portion of a crater floor.

On September 11, LCROSS mission planners announced that they had targeted a smaller, more northerly crater named Cabeus A. But later that month, analyses of new data from instruments aboard LRO, together with archival measurements from NASA's Lunar Prospector mission of the late 1990s, indicated that the larger Cabeus crater was a better bet.

"The sweet spot for ground-based telescopes lies about two kilometers above the floor of Cabeus," Wright explained. "There, sunlight streaming through a depression in the crater rim will light up the plume while the rest of the crater remains in shadow."

WASHINGTON — A NASA probe slammed into the moon Friday, in a bid to blast out a curtain of debris in which scientists hope to detect signs of water ice.

The $79 million LCROSS spacecraft, preceded by its Centaur rocket stage, impacted the lunar surface at the large south pole crater Cabeus at 7:31 a.m. EDT (1131 GMT) in what NASA Chief Scientist Jim Garvin called "the ultimate physics experiment."

"We keep finding evidence that there is water [on the moon]," NASA Administrator Charles Bolden told SPACE.com here. To find more with LCROSS "would be incredibly good news. It would be another place we can send humans," he added. Bolden said he had been following the last steps of the mission throughout the night.

The LCROSS probe beamed live images of the moon as its Centaur rocket stage headed for impact before making its own death plunge four minutes later. The two probes have crashed, mission managers assured, but whether LCROSS caught the much touted flash of the Centaur's impact was not immediately clear.

"I can certainly report there was an impact," NASA's principal investigator Tony Colaprete told reporters after the $79 million lunar crashes. "We saw the impact, we saw the crater ... we have the data we need to actually address the questions we set out to address."

The target crater became larger and larger, with its bumpy relief becoming clearer, in the broadcast images as LCROSS sped toward the moon. There were gasps and then claps from the Newseum crowd here as the viewing screen filled with the image of the crater and then went white. Laughs followed as the Flight Director at Ames confirmed the successful impact and then proudly stood up in a televised broadcast.

Mission scientists watched the crash primarily from the probe's operations center at NASA's Ames Research Center in Moffett Field, Calif., but astronomers and amateur skywatchers also tuned in at observatories and other sites around the world — including here at the Newseum, where more than 300 people watched the NASA impact broadcast on a huge 40-foot screen.

"This is the biggest screen I've ever seen," said one of the scores of people in the crowd of NASA employees, members of the press and public, including several bleary-eyed children.

Among the crowd were Apollo 11 astronaut Buzz Aldrin and Chip Cronkite, the son of late CBS TV news anchor Walter Cronkite, to whom the mission is dedicated.

"We hope this is just the first of many oases we find," Cronkite said.

NASA launched LCROSS — short for Lunar Crater Observation and Sensing Satellite — and the powerful Lunar Reconnaissance Orbiter (LRO) in June to hunt for evidence of water and ice on the lunar surface.

Ice on the moon

Scientists think that pockets of water ice might exist in the permanently shadowed craters of the lunar south pole — thought to potentially be the coldest places in the solar system. Water has already been detected on the moon by a NASA-built instrument on board India's now defunct Chandrayaan-1 probe and other spacecraft, though it was in very small amounts and bound to the dirt and dust of the lunar surface.

NASA plans to return astronauts to the moon by 2020 for extended missions on the lunar surface. Finding usable amounts of ice on the moon would be a boon for that effort since it could be a vital local resource to support a lunar base.

Even if LCROSS does not turn up clear proof of water ice, that would be a major find, mission scientists said. It could mean that ice on the moon is not as uniformly distributed as suspected, or that water exists in concentrations too low to be measured by LCROSS instruments — which would have repercussions for its value as a resource to astronauts, they added.

The LCROSS impact was also watched by several satellites that normally monitor Earth and spacecraft like the Hubble Space Telescope, Sweden's Odin observatory and LCROSS's sister spacecraft, the LRO probe, which were due analyze the debris after the impact to look for signs of water ice.

"All eyes are on LCROSS today," Bolden said during remarks before the impact.

The crashes were expected to kick up tons of moon dirt and carve a new crater within the 60-mile (98-km) wide Cabeus. That new crater could be as large as 66 feet (20 meters) wide and 13 feet (4 meters) deep. In a pass over the lunar south pole later today, LRO will image the LCROSS impact crater.

Some 350 tons of moon dirt was expected to be blasted nearly 6.2 miles (10 km) above the lunar surface. Unlike past moon crashes by other probes, like Japan's recent Kaguya mission, LCROSS slammed into the lunar surface at a steep angle and was slated to kick material up high enough to be illuminated by the sun as seen from Earth and other spacecraft.

Seasoned skywatchers on Earth equipped with 10 to 12-inch telescopes had a chance to spot the crash on their own, if they knew where to look.

"There's not going to be these grand, spectacular images of ejecta flying, kind of what you've seen in animations or cartoons," Colaprete told reporters Thursday. "It's going to be more of a muted shimmer of light, but that muted shimmer of light contains all the information we need to answer our questions."

Scientists don't know yet whether or not they've detected water in the LCROSS ejecta, as it is expected to take some time to analyze the data.

A NASA probe that slammed into the moon's south pole Friday managed to spot the artificial crater carved into the pristine lunar terrain minutes earlier by its partner craft, but scientists have not yet confirmed if the two crashes kicked up a giant plume containing any signs of water ice — a main goal.

NASA's LCROSS spacecraft slammed a 2.2-ton empty rocket stage — the equivalent of a sport utility vehicle — into a crater called Cabeus at 7:31 a.m. EDT (1131 GMT) and recorded the resulting explosion just before making its own death dive and crater four minutes later.

But in those four crucial minutes, the five cameras and four other instruments on the LCROSS shepherding spacecraft recorded the flash of the rocket stage's impact and a telltale sign of the leftover crater. What remains to be seen is whether the crashes created the vast plume of moon dirt that scientists predicted would blast out of the crater up to heights of 6.2 miles (10 km), where it could be lit up by the sun and visible to observers on Earth.

"We saw a crater. We saw a flash," NASA's principal investigator Tony Colaprete told reporters after the $79 million lunar impacts. "So something had to happen in between."

Colaprete said he's thrilled, rather than disappointed like some observers not with the mission team, and had some thoughts on the missing plume.

The plume may have ejected out on an unexpected angle or not risen high enough to be spotted by spacecraft and observers on Earth, Colaprete said, adding that researchers will know more after an in-depth look at the data. The crater left by the Centaur upper stage is about the same size as scientists predicted — around 66 feet (20 meters) wide.

Lunar smackdown

Colaprete and other LCROSS researchers repeatedly warned that the LCROSS impacts would be difficult to spot from Earth. On Thursday, they described it as seeing "blackness get less black" as the plume exploded outward.

Scientists hoped to be able to scan that portion of the plume from space and Earth to determine if any water ice was present in the debris cloud. Finding proof of buried water ice — long suggested by the presence of hydrogen-bearing material at the lunar south pole — could be a boon for NASA since it could be a potential resource for future astronauts.

Last month, scientists announced definitive proof that small amounts of water exist elsewhere on the moon in a molecular form attached to lunar dirt. NASA launched LCROSS — short for Lunar Crater Observation and Sensing Satellite — in June along with a powerful orbiter to seek out evidence of water and ice on the moon.

"The moon we thought we knew is not the moon we know now," NASA's chief lunar scientist Mike Wargo told SPACE.com after the LCROSS crashes. "The results that we'll get from LCROSS are an important piece in the puzzle of something that is pretty darn new, the hydration cycle on the moon."

And there are already some other intriguing details puzzling LCROSS scientists.

While no obvious sign of a debris cloud have been confirmed, spectra — measurements taken in non-visible wavelengths of light — indicate a signal that suggests an ejecta cloud occurred, Colaprete said. More time is needed to analyze the spectra findings, he added.

During the four minutes between the Centaur crash and the shepherding spacecraft's impact, there was also a strong sodium signal, hinting at some interaction between the impact and the moon's tenuous exosphere of surface material.

"I've got to say that I was blown away by how long this little spacecraft lasted," Colaprete added.

The view from Earth

About 21 professional observatories and a host of amateur skywatchers stretching across the western United States, Hawaii and some overseas sites had fair weather to spot the cloud, but have not yet reported a visible confirmation of the plume.

"We're just looking at the very preliminary images to get a sense of the types of data that have been collected," said Jennifer Heldmann, head of the LCROSS observation campaign. "But it's too early to tell, to make that determination."

Some observatories have already released their early images of the LCROSS lunar crash. Others recorded videos of the Centaur rocket stage and the target crater Cabeus, a 68-mile (98-km) crater partly covered by a permanent shadow because of its location at the lunar south pole.

The Hubble Space Telescope and other satellites and spacecraft, including NASA's Lunar Reconnaissance Orbiter that launched with LCROSS and is currently circling the moon, are also tracking the aftermath of the lunar crashes.

Heldmann said that right now, NASA is awash in data from the moon crashes, especially since all the sites reported pristine viewing conditions.

"We have images. We have video. We have graphs with wavy lines that scientists love," Heldmann said. "We have something for everyone."